My husband has a 2004 WR450F and it won't start. When we try to kick start the bike we can hear it trying to fire, but nothing happens. We took the carb off, and I took it apart to make sure nothing was plugged up or dirty (which I am not an expert on doing). We then put the carb back on and tried to start it. It took a good bit of kick starting but it finally fired up for about 20 seconds, and then died. It wants to fire up, but nothing. We know the battery isn't holding a charge, but our mechanic told us the bike should run even with the battery being junk. Anyone have any tips on what might be wrong?! A little note, my old man put a little of his chainsaw gas in the bike.